Liquid discharge nozzle with inverted cone discharge pattern

ABSTRACT

An aerating liquid discharge nozzle containing no moving parts and including a hollow body defining a liquid inlet at one end and an outlet opening at the other end. The body has an internal duct arranged in communication with both the inlet and outlet ends of the body. A plug, having substantial length between opposite end surfaces, is disposed across the chamber adjacent the body outlet end and has a hole therethrough coaxially of the duct, which hole is substantially smaller in area than the area of the duct. A tube extends axially of the body within the duct and has an open upper end adjacent the plug, a closed lower end, and an inner chamber defined between the upper and lower ends of the tube. A plurality of slots extend through the sidewalls of the tube and are spaced apart around the circumference of the tube. Liquid introduced into the tube through the slots flow spirally around and along the interior of the tube to the plug hole and to the exterior of the nozzle through the hole.

I United States Patent 11113,630,443

[72] Inventor John 0. Hruby, Jr. [56] References Cited UNITED STATES PATENTS 25$- 61 3,091,398 5/1963 Hruby, Jr 239/010. 16 [45] Patented Dec. 1971 3,481,541 12/1969 Hruby, Jr.... 239/17 Assume Cor" 3,330,486 7/1967 Semple 239/ 17 X Burbank, Call. Primary Examiner-M. Henson Wood, Jr. Original ap lication Dec. 9, 1968, Ser, No. Assistant ExaminerThomas C. Culp, Jr. 784,541, my hum No, 3,558,053, whi h Att0rney-Christie, Parker 81'. Hale Is a continuation-impart of application Ser. No. 691,111,]Jec. l, 1967, now abandoned is conflnufiorhwutoi ABSTRACT: An aeratmg hqmd dlscharge nozzle conta ning .ppuauon Sen 492,389 M 4, 1965, no movmg parts and mcludmg a hollow body defining a llqu1d w .b-nM'DiW d this inlet at one end and an outlet opening at the other end. The puma July 1970 sen No. 52,579 body has an internal duct arranged in communication with both the inlet and outlet ends of the body. A plug, having substantial length between opposite end surfaces, is disposed [54] LIQUID DISCHARGE NOZZLE WITH INVERTED across the chamber adjacent the body outlet end and has a CONE DISCHARGE PATTERN hole therethrough coaxially of the duct, which hole is substan- 19 Clalms, 5 Drawing Figs. tially smaller in area than the area of the duct. A tube extends axially of the body within the duct and has an open upper end [52] 239 9"239 adjacent the plug, a closed lower end, and an inner chamber [51] H Bosh 17,08 defined between the upper and lower ends of the tube. A plu- 501 Field of Search 239/16, 17, sidwau' and 19, 22, 428.5, DIG. l, DIG. l6

spaced apart around the circumference of the tube. Liquid introduced into the tube through the slots flow spirally around and along the interior of the tube to the plug hole and to the exterior of the nozzle through the hole.

law

14 /6 z I I 1 1 0 M a f I /7 t I 25 i i 1 4% 1-1 1 1 1 I t 1 3 1 3 H 1 3 i I 1 27- i "27 LIQUID DISCHARGE NOZZLE WITH INVERTED CONE DISCHARGE PATTERN CROSS-REFERENCE TO RELATED APPLICATION This application is a division of Ser. No. 784,541, filed Dec. 9, 1968, now U.S. Pat. Ser. No. 3,558,053 issued on Jan. 26, 1971 as a continuation-in-part of copending application, Ser. No. 691,111 (now abandoned), filed Dec. 8, 1967 as a continuation-in-part of Ser. No. 492,389 (now abandoned), filed Oct. 4, 1965.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to liquid handling and, more particularly, to nozzles for discharging aerated liquid in a predetermined pattern. Nozzles according to this invention are characterized by the absence of moving parts in the liquid stream and are useful as ornamental fountain nozzles.

2. Description of the Prior Art In ornamental fountain arrangements which are to be viewed during the day without illumination by artificial light, it is desired that the discharged water be aerated as fully as possible in order that the water discharge pattern may be readily visible. Aerating fountain heads or nozzles are known. Present fountain heads, however, produce only a limited number of water discharge patterns. Many existing aerating fountain heads do not produce sufficient aeration of the water discharged from them. Moreover, many existing aerating nozzles contain moving parts which wear as the nozzle is operated. In other cases, existing aerating nozzles require critical clearances in the nozzle openings to produce the desired aeration; these clearances either become worn by erosion as the nozzle is operated, or clogged by foreign particles in the liquid passing through the nozzle head, thus adversely affecting the nozzle-aerating efficiency.

For efficiency of operation, an aerating fountain nozzle should produce the appearance of discharging a quantity of water even though the quantity of water actually passed through the nozzle is relatively moderate. When this desired condition is obtained, a small pump may be used, thus resulting in a fountain which is economical to operate. Also, in order that they may be used in populated areas, aerating fountain nozzles should produce as little mist or fine spray as possible; mist is readily transported by slight breeze out of the fountain area to locations where viewers may be positioned. Mist also tends to mask the basic fountain discharge pattern and thus detracts from the aesthetic effect desired in the fountain.

The design of aerating liquid nozzles is often more of an art than a science, especially where it is desired that the aerated liquid discharged from the nozzle follow a predetermined path from the nozzle throughout a relatively wide range of liquid pressures applied to the nozzle, and where the discharge is to be used to produce an ornamental effect. The use of techniques and principles which are effective in gas mixing nozzles, wherein two or more gases are mixed in the nozzle structure and are discharged as a mixture, is practical in only random situations in'aerating liquid nozzles because of the widely different physical properties between gases and liquids.

SUMMARY OF THE INVENTION This invention provides a simple, rugged, effective and efficient aerating nozzle which is particularly useful in ornamental fountain arrangements. The nozzle contains no moving parts which may wear as the nozzle is operated. Moreover, no critically sized apertures are provided in the nozzle, and thus water erosion and the presence of foreign particles in the water passed through the nozzle have little effect, if any, upon the aerating efficiency of the nozzle. The nozzle produces the appearance of a massive discharge stream even though the actual volume of water passed therethrough is moderate. Moreover, nozzles according to this invention provide liquid discharge patterns which are essentially free of objectionable 'mist or fine spray and which are readily visible because of the high degree of aeration of the nozzle discharge and freedom from mist.

Generally speaking, the invention provides an aerating liquid discharge nozzle comprising an elongate body having opposite open ends defining a duct therethrough between a liquid inlet opening defined at one end of the body and a liquid outlet opening defined across the open other end of the body. A plug is disposed across the duct along the body from the other open end of the body and is secured from movement along the length of the body, the plug being engaged about its periphery with the inner walls of the duct. The plug has a hole therethrough substantially coaxially of the duct, the hole, at least adjacent the other end of the body, having an area substantially less than the cross-sectional area of the duct. A tube extends axially of the body within the duct on the side of the plug toward the liquid inlet opening. The tube has an open end adjacent the plug, a closed lower end, and an inner chamber defined between the upper and lower ends of the tube. A plurality of slots extends through the sidewalls of the tube and are spaced apart around the circumference of the tube, the slots providing communication between the liquid inlet opening and the interior of the tube and are arranged so that liquid admitted to the tube through the slots flows spirally around and along the tube toward the plug.

BRIEF DESCRIPTION OF THE DRAWINGS The above mentioned and other features of the present invention are more fully set forth in the following detailed description of the invention, the description being presented in conjunction with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation view of an aerating liquid discharge nozzle according to this invention;

FIG. 2 is a top plan view taken along lines 2-2 of FIG. 1;

FIG. 3 is a cross-sectional plan view taken along lines 33 of FIG. 1;

FIG. 4 is an elevation view of the water discharge pattern produced by the nozzle shown in FIG. I; and

FIG. 5 is a fragmentary cross-sectional elevation view of another nozzle similar to the nozzle shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An aerating liquid discharge nozzle 10, which is particularly useful in ornamental fountains and shown in FIG. 1, includes an elongate, hollow, tubular body 11 defining an elongate, circularly cylindrical ductlike internal chamber 12. The body has an internally threaded open lower end I3 to adapt the body to be securely connected to a suitably sized water discharge pipe or the like (commonly known as a riser pipe) through which water at suitable pressure is supplied to the nozzle. The lower end of the body defines a liquid inlet opening to chamber 12. The cylinder defined by theinner wall of the body is open across its entire extent at an open upper end 14 of the body. A plug 15 having substantial thickness, relative to the inner diameter of the body, between opposite parallel and preferably planar end surfaces 16 and I7 is disposed across the interior of the body adjacent the upper end of the body. A water outlet passage 18 is formed through the plug axially of the body and has a cross-sectional area substantially less than the cross-sectional area of chamber 12. In nozzle 10, as in nozzle 35 of FIG. 5 (described below), the area of the liquid inlet opening to the nozzle is at least as great, and preferably greater than, the area of the liquid flow passage through the plug. The passage has substantially equal areas at all locations along its length between the end surfaces of the plug. As with nozzle 35, nozzle 10 is devoid of any structure spanning the duct downstream of plug 15. That is, after water passes plug 15, it does not pass through any additional structure, other than the body itself, in emerging from the nozzle.

As shown best in FIG. 2, passage 18 is defined by a combination of a circularly cylindrical opening 19 formed through the plug coaxially of the body and by a plurality of substantially identical semicircular grooves or flutes 20 which open concave to opening 19 along the entire length of the plug; the grooves open to the opposite end surfaces of the plug. Preferably, as shown in FIG. 2, the grooves are uniformly spaced around the circumference of opening 19 at a distance greater than the diameter of the grooves. Accordingly, a generally square ended rib 21 is defined between each adjacent pair of grooves. Thus, the grooves are distinctly spaced from each other around the central opening through the plug and the generation of thin sheets of water is avoided in the discharge pattern of noule 10. It has been found that the presence of thin sheets of water in the discharge pattern degenerate remote from the head into mist or fine spray which is objectionable for the reasons set forth above.

A hollow cylindrical tube 23 extends axially into chamber 12 away from plug 15 toward the inlet opening to chamber 12. The tube is disposed concentric to the axis of the body and has a closed end 24 spaced away from the plug. The interior of the tube defines a circularly cylindrical chamber 25. The outer diameter of the tube is substantially less than the inner diameter of the body so that, along the length of the tube, chamber 12 has an annular configuration. In nozzle 10 the tube has an upper end 26 abutted against plug lower end surface 17. A plurality of slots 27, elongated in the direction of the length of the tube end and spaced apart around the circumference of the tube, extend through the sidewalls of the tube to provide the sole communication between chambers 12 and 25. The slots, as shown in FIG. 3, extend from the exterior of the tube into substantial tangency with the circularly cylindrical inner walls of the tube. All of the slots communicate with the interior of the chamber in the same angular sense, i.e., all the slots are angled either clockwise or counterclockwise to the tube. The tube is mounted in an axial bore 28 of an annular ring 29 which is disposed across the interior of the body immediately below plug 15. An O-ring 30 is engaged between ring 29 and the body to prevent liquid from leaking between the ring and the body. Accordingly, water flow through the nozzle is solely along a path through the open lower end of the body into chamber 12, through slots 27 into chamber 25, spirally around and upwardly along the inner surfaces of tube 23, and through outlet opening 18 to the exterior of the nozzle.

ln small nozzles 10, it is preferred (as shown in FIG. 2) that the inner diameter of tube 23 be greater than the diameter of hole 19, but less than the diameter of passage 18 as measured across the portions of the grooves spaced farthest from the axis of the nozzle, for best aeration of water passed through the nozzle. 1n larger nozzles 10, however, it is preferred that the diameter of hole 19 be greater than the inner diameter of tube 23. For example, in the nominal 29% inch nozzle described in detail below, hole 19 is smaller than the crosssectional area of tube 23. In a nominal 4-inch nozzle, however, where the tube may have an inner diameter of 2 /16 inches, hole 19 preferably has a diameter of 2% inches. It is also preferred that the length of the plug between opposite end surfaces 16 and 17 be substantially equal to the maximum transverse dimension of the passage through the plug. In other words, the hole through the plug is substantially square in elevation, as shown in FIG. 1.

FIG. 4 shows nozzle and a water discharge plume or pattern 31 produced by such a nozzle when water is supplied under pressure to the nozzle. When the nozzle is vertically oriented, the discharge plume has a symmetrical conical configuration. The nozzle discharge is readily visible in daylight from a considerable distance since the water which forms the discharge plume is highly aerated. The discharge pattern is remarkably free of mist which might mask the basic pattern or which might, in a breeze, wet nearby observers of the fountain.

As water enters into chamber 25 from chamber 12 through angularly oriented slots 27, this water is caused to flow spirally around and upwardly along the surfaces of tube 23 and is believed to form a vortex into which is drawn air from the exterior of the nozzle. As the spirally flowing water emerges from tube 23, it encounters ribs 21 which abruptly turn the water emerging from the tube into grooves 20 and cause the water to be thoroughly mixed with air drawn into the vortex. As the water emerges from the upper end of passage 18, it passes over the substantially right-angled shoulder defined by the intersection of plug upper surface 16 with the vertical walls of the outlet opening. Accordingly, the water emerging from the plug separates cleanly from the plug and does not tend to flow along the upper surface of the plug as might be the case were the walls of passage 18 faired into the upper surface of the plug. The result is that discharge plume 31 contains a minimum amount of mist or fog over a wide range of applied water pressures and flow rates.

FIG. 5 illustrates a nozzle 35 which is similar to nozzle 10, except that nozzle 35 includes a plug 36 spaced above the upper end of tube 23 adjacent the open upper end of body 11. Accordingly, a circularly cylindrical chamber 37 is provided between plug 35 and ring 29. Chambers 12 and 37 have equal diameters. Also, plug 36 has a circularly cylindrical passage 38 formed axially through it between opposite parallel plug end surfaces 39 and 40; no grooves, such as grooves 20 of nozzle 10, open to passage 38. As noted above, for best aeration the diameter of passage 38 can be slightly less than (this case is shown in FIG. 5), equal to, or greater than the inner diameter of tube 23. Preferably, the distance between the end surfaces of the plug is substantially equal to at least the diameter of the hole defining passage 38 and may be greater than the diameter of the hole as shown in FIG. 5. Nozzle 35 produces a liquid discharge plume substantially identical to plume 31 produced by nozzle 10 and is characterized by the same absence of mist or fog as is encountered in nozzle 10.

It is preferred that the upper end surface of plugs 15 and 36 be coextensive with the upper end of the tubular body within which the plug is mounted. In the event, however, that either one of plugs 15 or 36 is spaced below the open upper end of the body, as shown in FIGS. 1 and 5, care should be taken to locate the plug sufficiently close to the upper end of the body that the water emerging from the plug outlet passage does not interact with the rim of the body at its extreme upper end. Such interaction of the water emerging from the plug outlet passage with the upper end of the body produces a mist or fog and degrades the clean profile of the nozzle discharge plume.

A nozzle 10 having a diameter of chamber 12 of 2 5/16 inches, a diameter of chamber 25 of 1% inches, a plug length of 2 defining an outlet passage consisting of a circular hole of 1% inches diameter in combination with six grooves having a radius of A inch formed in the walls of the l /a-inch hole has been successfully operated over a wide range of applied water pressures to produce a water discharge plume 31 as shown in FIG. 4. When gallons of water per minute are passed through the nozzle, the discharge pattern produced by the nozzle is 1 1 high and 14 feet in diameter; the nozzle head loss or back pressure is only 10 pounds per square inch.

ln nozzles 10 and 35, it is preferred that body 11, tube 23 and plugs 15 and 36 be fabricated of polyvinyl chloride. Such a material is resistant to erosion by water flowing through the nozzle at high pressures.

From the foregoing it is apparent that this invention provides a novel, highly useful water discharge nozzle particularly useful in ornamental fountain arrangements, but also useful in other applications as desired. Each of the nozzles described above produces a high degree of aeration in the liquid passing through it without relying upon any moving parts or critically sized openings to accomplish this aeration. Preferably, the nozzles are fabricated entirely from polyvinyl chloride or some similar plastic; thus these nozzles are highly resistant to the effects of water erosion and have long life expectancies under adverse conditions. The nozzles have in common the feature that the water discharge patterns produced by the nozzles are remarkably free of mist, fog, or fine spray.

In the foregoing description, specific geometrical arrange ments and dimensional relationships, and even specific dimensions have been set forth merely for the purposes of example and explanation of this invention; only in certain instances have specified features of the nozzle been stated to be critical. Accordingly, it will be apparent to those skilled in the art that modifications and alterations in the above-described nozzles may be made without departing from the scope of .this invention. As noted above, it will also be apparent to those skilled in the pertinent art that features of one described nozzle may be applied to another described nozzle without departing from the teachings of the invention, especially where a characteristic of the one nozzle is desired in the other.

What is claimed is:

1. An aerating liquid discharge nozzle comprising:

a. an elongate body defining a duct therethrough between a liquid inlet opening defined at one end of the body and a liquid outlet opening defining across the other end of the body,

b. a plug disposed across the duct adjacent the other end of the body with its circumference sealed to the walls of the duct, the plug having substantial length between the opposite ends thereof relative to the diameter of the duct and having a hole therethrough coaxially of the duct,

0. a tube extending in spaced relation to the duct walls substantially coaxially of the duct awayfrom an open end sealed to the body adjacent the plug to a closed end adjacent the body liquid inlet opening, the interior of the tube communicating with the exterior of the nozzle through the plug hole, and

d. means for introducing into the tube only from the space between the tube and the duct walls liquid supplied to the nozzle through said liquid inlet opening in such manner that liquid introduced into the tube flows spirally around and along the interior ofthe tube toward the plug hole,

e. the nozzle being devoid of any structure extending within thetube and through the hole in the plug.

2. A nozzle according to claim 1 wherein the surface of the plug adjacent the duct liquid outlet opening, at least around the periphery of the opening of the hole to such surface, is substantially normal to the length of the hole and defines sharp comers with the walls of the hole.

3. A nozzle according to claim 1 wherein the means for introducing liquid into the tube comprises a plurality of slots through the tube walls.

4. A nozzle according to claim 3 wherein the slots are extended along the length of the tube and open through the tube substantially tangent to the inner walls of the tube.

5. The nozzle according to claim 1 wherein the open end of the tube is spaced from the plug along the duct.

6. The nozzle according to claim 1 wherein the open endof the tube abuts the plug.

7. A nozzle according to claim 1 wherein the nozzle is devoid of structure spanning the duct between the plug and the other open end of the body.

8. A nozzle according to claim 1 wherein the plug has a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct.

9. A nozzle according to claim 8 wherein the hole through the plug is circularly cylindrical and has a diameter approximating but less than the inner diameter of the tube.

10. A nozzle according to claim 9 wherein the open end of the tube is spaced along the duct from the plug.

11. A nozzle according to claim 9 wherein the hole has a diameter substantially equal to the length of the hole through the plug.

12. A nozzle according to claim 8 wherein the hole is a combination of a circularly cylindrical passage having a diameter approximating the inner diameter of the tube and a plurality of flutes uniformly spaced around the passages and open to the passages and the ends of the plug.

13. A nozzle according to claim 12 wherein the flutes are of semicircular configuration.

14. A nozzle of claim 12 wherein the width of the openings of the flutes to the passage about the circumference of the passage is less than the spacing circumferentially of the passage between corresponding locations of adjacent flutes.

15. A nozzle according to claim 12 wherein the distance from the axis of the passage radially to the flutes is substantiallg' one-half the distance between the ends of the lug.

1 A nozzle according to claim 12 wherein the iameter of the passage is less than the inner diameter of the tube and the radius of the passage and the depth of the flutes is greater than the inner radius of the tube.

17. A nozzle according to claim 16 wherein the open end of the tube abuts the plug.

18. A nozzle according to claim 12 wherein the open end of the tube abuts the plug.

19. An aerating liquid discharge nozzle comprising:

a. an elongate body defining a duct therethrough between a liquid inlet opening defined at one end of the body and a liquid outlet opening'defined across the other end of the body,

. a plug disposed across the duct adjacent the other end of the body with its circumference sealed to the walls of the duct, the plug having a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct and having a hole therethrough coaxially of the duct, the hole being defined as a combination of a circularly cylindrical passage having a diameter approximating the inner diameter of a tube disposed in the duct adjacent the plug and a plurality of flutes uniformly spaced around the passage and open to the passage and the ends of the plug,

c. a tube extending in spaced relation to the duct walls substantially coaxially of the duct away from an open end sealed to the body adjacent the plug to a closed end adjacent the body liquid inlet opening, the interior of the tube communicating with the exterior of the noule through the plug hole, and

d. means for introducing into the tube from the space between the tube and the duct walls liquid supplied to the nozzle through said liquid inlet opening in such manner that liquid introduced into the tube flows spirally around and along the interior of the tube toward the plug hole.

mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,630,443 Dated December 28, 1971 Inventor) John O. Hruby, Jr.

It is certified that error appears in 'the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 4'2, after "2" read --1'.nches--.

Column 5, line 11, for "defining" read --defined--.

Column 6, line 13, for "of" (first occurrence) read -according to---.

Signed and sealed this 26th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. An aerating liquid discharge nozzle comprising: a. an elongate body defining a duct therethrough between a liquid inlet opening defined at one end of the body and a liquid outlet opening defined across the other end of the body, b. a plug disposed across the duct adjacent the other end of the body with its circumference sealed to the walls of the duct, the plug having substantial length between the opposite ends thereof relative to the diameter of the duct and having a hole therethrough coaxially of the duct, c. a tube extending in spaced relation to the duct walls substantially coaxially of the duct away from an open end sealed to the body adjacent the plug to a closed end adjacent the body liquid inlet opening, the interior of the tube communicating with the exterior of the nozzle through the plug hole, and d. means for intRoducing into the tube only from the space between the tube and the duct walls liquid supplied to the nozzle through said liquid inlet opening in such manner that liquid introduced into the tube flows spirally around and along the interior of the tube toward the plug hole, e. the nozzle being devoid of any structure extending within the tube and through the hole in the plug.
 2. A nozzle according to claim 1 wherein the surface of the plug adjacent the duct liquid outlet opening, at least around the periphery of the opening of the hole to such surface, is substantially normal to the length of the hole and defines sharp corners with the walls of the hole.
 3. A nozzle according to claim 1 wherein the means for introducing liquid into the tube comprises a plurality of slots through the tube walls.
 4. A nozzle according to claim 3 wherein the slots are extended along the length of the tube and open through the tube substantially tangent to the inner walls of the tube.
 5. The nozzle according to claim 1 wherein the open end of the tube is spaced from the plug along the duct.
 6. The nozzle according to claim 1 wherein the open end of the tube abuts the plug.
 7. A nozzle according to claim 1 wherein the nozzle is devoid of structure spanning the duct between the plug and the other open end of the body.
 8. A nozzle according to claim 1 wherein the plug has a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct.
 9. A nozzle according to claim 8 wherein the hole through the plug is circularly cylindrical and has a diameter approximating but less than the inner diameter of the tube.
 10. A nozzle according to claim 9 wherein the open end of the tube is spaced along the duct from the plug.
 11. A nozzle according to claim 9 wherein the hole has a diameter substantially equal to the length of the hole through the plug.
 12. A nozzle according to claim 8 wherein the hole is a combination of a circularly cylindrical passage having a diameter approximating the inner diameter of the tube and a plurality of flutes uniformly spaced around the passages and open to the passages and the ends of the plug.
 13. A nozzle according to claim 12 wherein the flutes are of semicircular configuration.
 14. A nozzle of claim 12 wherein the width of the openings of the flutes to the passage about the circumference of the passage is less than the spacing circumferentially of the passage between corresponding locations of adjacent flutes.
 15. A nozzle according to claim 12 wherein the distance from the axis of the passage radially to the flutes is substantially one-half the distance between the ends of the plug.
 16. A nozzle according to claim 12 wherein the diameter of the passage is less than the inner diameter of the tube and the radius of the passage and the depth of the flutes is greater than the inner radius of the tube.
 17. A nozzle according to claim 16 wherein the open end of the tube abuts the plug.
 18. A nozzle according to claim 12 wherein the open end of the tube abuts the plug.
 19. An aerating liquid discharge nozzle comprising: a. an elongate body defining a duct therethrough between a liquid inlet opening defined at one end of the body and a liquid outlet opening defined across the other end of the body, b. a plug disposed across the duct adjacent the other end of the body with its circumference sealed to the walls of the duct, the plug having a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct and having a hole therethrough coaxially of the duct, the hole being defined as a combination of a circularly cylindrical passage having a diameter approximating the inner diameter of a tube disposed in the duct adjacent the plug and a plurality of flutes uniformly spaced around the passage and open to the passage and the eNds of the plug, c. a tube extending in spaced relation to the duct walls substantially coaxially of the duct away from an open end sealed to the body adjacent the plug to a closed end adjacent the body liquid inlet opening, the interior of the tube communicating with the exterior of the nozzle through the plug hole, and d. means for introducing into the tube from the space between the tube and the duct walls liquid supplied to the nozzle through said liquid inlet opening in such manner that liquid introduced into the tube flows spirally around and along the interior of the tube toward the plug hole. 